820-3332-A doesn't work properly with external display

djdblaster

New member
This board has problems when external Display is hooked up to Thunderbolt port. Internal and external displays stay black until you close and open the lid a few times. Then they both work properly.
 

djdblaster

New member
I?m not sure what customer uses. I do have 85W.
I only have board and display for this one. I guess SMC_LID won?t work without housing or I could use a magnet somewhere?
 

2informaticos

Administrator
Staff member
You don't need to trigger lid sensor.
Just check if its signal remains steady high.

Lid sensor is located on J5250, near audio connector.
 

djdblaster

New member
Sorry, wrong information. Just got the board in front. It actually doesn't show picture when starting, but it does when lid is closed and opened a couple of times, while Thunderbolt is connected.
 
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djdblaster

New member
No internal SSD at the moment. I'm testing with an external drive with High Sierra. Should I install El Capitan on it? How about SMC reset?
 

djdblaster

New member
SMC_LID 3.42V with display only connected, outside the housing.

SMC and PRAM no luck.

Do I still have to try El Capitan? I don't see how that would be connected to no image and no backlight. I would be happy with a question mark folder screen.
 

djdblaster

New member
I tried with El Capitan. Nothing on screen.

Laptop starts with black screen, nothing can be seen using flashlight.

For backlight LCD_BKLT_EN is missing. Goes straight to U9100 (eDP MUX sheet). So something with MUX then since I see HDMI and DP involved on this sheet?
 

2informaticos

Administrator
Staff member
Do you always get normal image on internal LCD?
The problem appears only when external monitor is connected?
 

djdblaster

New member
No. In order to get image on internal display, external has to be connected and lid closed/open a few times. Then it works normal.
 

2informaticos

Administrator
Staff member
Understood now.
For the repair, continue with internal LCD only.
Check SMC_LID and voltage for pins 28-30 of J9000.
In the first few seconds, you must get 5V there; even without LCD connected.
If LCD is connected, LCD_HPD should go high.
Once LCD is recognized by PCH, all these should stay high and also image/backlight must come on.
 
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